Notifies the receiver that the fetched results controller is about to start processing of one or more changes due to an add, remove, move, or update.
- iOS 4.0+
- macOS 10.12+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Data
The fetched results controller that sent the message.
This method is invoked before all invocations of
controller: have been sent for a given change event (such as the controller receiving a